Elephant gun's ability reads:
Zap, pay 2 – Target hired Beastie Monster gains 3 [power] for this fight. If this is zapped during your cooldown, move this to the top of your deck, face-down.

The wording for this card is confusing because the second sentence appears to be inside the entire zap ability. As in: Zap, pay - everything else on this card now takes effect.

So looking at the second sentence, does elephant gun move to the top of your deck even if it's tapped for reasons other than using its zap ability? If so, shouldn't the card be formatted so that the second sentence is in its own paragraph?

The second sentence of the ability is considered to always be in effect, so it will trigger no matter the reason that Elephant Gun is zapped. It probably should have had a line break to make that clearer.